天然水中优势菌胞外聚合物及其中主要成分对铅的吸附

Adsorption of Lead(Ⅱ) by Extracellular Polymer of Superiority Bacteria in Natural Water and Its Main Components

研究了吉林省长春市南湖天然水环境中生物膜胞外聚合物及由其分离得到的胞外多糖和胞外蛋白对铅的吸附特性,讨论了时间、pH值、其它共存金属离子等对其吸附的影响;初步探讨了胞外多糖和胞外蛋白吸附铅的反应机理。结果表明,3种吸附剂对铅的吸附量在pH=6时最大,分别为23.64、15.8和3.48 mg/g;吸附体系均在6 h以后达到吸附平衡;共存金属离子镉对铅的吸附有影响。胞外聚合物及其中的胞外多糖和胞外蛋白对铅的吸附过程符合Langmuir和Freundlich热力学方程。胞外聚合物中胞外多糖对铅的吸附所作贡献大于胞外蛋白。胞外蛋白的胺基、酰胺基,胞外多糖的羟基、酰胺基等是胞外聚合物吸附铅离子过程中起关键作用的化学基团。

The adsorption of lead（ Ⅱ ） on the extracellular polymer of superiority bacteria in natural water and its main components such as the exopolysaccharides and extracellular proteins were investigated. The main components were separated from the extracellular polymers of natural surface coatings cultivated in Changchun Nanhu Lake. The results show that three adsorbents＇ maximum adsorptive capacities are 23.64, 15. 8, 3.48 mg/g respectively when the solution original pH is 6. Both Langmuir and Freundlich isotherm equations could describe the thermodynamics adsorption processes of Pb on the extracellular polymers, exopolysaccharides and extracellular proteins. The existence of Cd affected the adsorption of Pb. The pH value also affected the adsorption processes. The mechanisms of adsorption of Pb were studied by infrared spectroscopy and the functional groups participated in the adsorption were identified, such as acetylamino group（—NHCOCH3） and amino-group（—NH2） of protein, hydroxyl group（—OH） of exopolysaccharide, etc. The results show that the biosorption ability of the exopolysaccharides is much higher than that of the extracellular proteins in the extra- cellular polymers.